ancient khasi burial site - small burial chamber (india)

From reading various old books about the Khasi people ancient funeral traditions, I believe that those square structures are small burial chamber, i.­e.­ small boxes where the ashes of the dead were kept, temporarily before a big ceremony (that did not take place too often) where they were moved into a larger Cinerarium (or large burial chamber), i.­e.­ basically a communal tomb holding the remains of all the Tribe's elders.­